There is a desire to detect the precise location and/or distance between particles on a micro-scale. One example of this resides in the use of fluorescent tags on linearized DNA strings based on a spatially modulated excitation. A system and method for detecting such particles or tags is described in U.S. Publication No. 2008/0181827 filed on even date herewith and incorporated herein by reference.
In an example of the cited application above, with reference to FIG. 1, a system 10 having a DNA string 12 with fluorescent tags 14 typically moves down a channel 16. The channel 16 guides the string 12 through an excitation stripe pattern 18 of a detection area 20. A detector 22 is suitably positioned relative to the detection area 20. The fluorescent signal resulting from the spatial modulation of the stripe pattern (or other suitable pattern, or technique, or architecture) is recorded vs. time as depicted in FIG. 2. A processing module 21 is also shown and is operative to conduct processing on the signal. The signal has a complex shape and, in one form, may be processed, for example, to resolve the positions of the tags 14. The positions of the tags are meaningful data in the contemplated DNA analysis. However, determining these positions becomes particularly difficult if two tags 14 are within the detection area at the same time (as in FIG. 3) and/or if the signal is noisy (as in FIG. 4).
The desire to determine particle position arises in other experimental environments. For example, the positions of particles are used in particle counting and cell sorting processes. Further, the actual or relative positions of particles on, for example, a microscope slide may be useful for certain diagnostic analyses. Examples of systems that may be used in such environments are also disclosed in U.S. Publication No. 2008/0181827 filed on even date herewith and incorporated herein by reference.